In colder climates, the build-up of ice on vehicle windshield wiper blades is a common problem. The ice causes the wiper blades to operate poorly which is an annoyance to drivers and can become a significant road hazard if the visibility of the driver through the windshield is significantly reduced.
Various wiper heating devices have attempted to overcome the problem of ice build-up on wiper blades by mounting a heating element in close proximity to or directly in engagement with the wiper blades. In order for the heating element to operate effectively it is generally required that the heating element directly engage the wiper blade. Known heating devices however generally mount the heating element integrally within the wiper or wiper blade such that replacement of the wipers requires replacement of the heating element or portions thereof. The periodical replacement of the wipers can thus be expensive and requires time consuming assembly.
U.S. Pat. No. 6,028,291 issued to Heisler and U.S. Pat. No. 4,497,083 issued to Nielsen each provide a heated windshield wiper system in which a heater element extends through the resilient wiper element of a wiper blade. In each instance a releasable connector supplies power to the heating element at one end of the resilient wiper element permitting the heating element and wiper element to be replaced without replacement of the entire wiper blade. In the event that the wiper blade requires replacement however considerable rewiring of the heating element is required. Heisler in particular provides a thermostat mounted on the wiper blade in a location requiring replacement of the electrical supply wiring in the event that the thermostat fails and requires replacement.
U.S. Pat. No. 3,408,678 issued to Linker provides a windshield wiper assembly in which a heating element extends along the resilient wiper element. The electrical supply wiring to the heating element includes selective couplings at a location where the wiper blade mounts on a supporting wiper arm such that the entire blade including the heating element can be replaced. The heating element and selective coupling in this instance however are required to be formed integrally with the wiper blade and therefore do not permit independent replacement of the various components of the wiper assembly.
Many other patents for example those listed in U.S. Pat. No. 7,721,382 (Malone) issued May 25, 2010 provide other designs of windshield wiper which can be heated. Examples are U.S. Pat. Nos. 6,137,084, 7,568,256, 5,572,765, 7,721,382, 6,591,443, 6,140,608, 6,058,664, 6,754,933, 7,401,379, and 5,787,543.
In U.S. Pat. No. 6,507,973 (Friesen) is shown an arrangement of this type where the electrical resistance is changed for different length heating elements.